The present invention relates to a DC fan motor that forces cold air to circulate inside of a freezer or a refrigerator as well as other DC fan motors for a ventilating fan or the like, and particularly to a downsized DC fan motor having a DC power source, and a method of manufacturing the same.
Freezing equipment, such as a refrigerator, is high power consuming equipment for household use; therefore, its power savings is desired. In freezing equipment, the compressor has the highest power consumption. The fan motor that forces cold air to circulate inside of the freezing equipment increases the workload of the compressor, which lowers the temperature inside of the freezing equipment, because the fan motor itself generates heat. For this reason, power savings of a fan motor is important for power savings of freezing equipment.
Prior Art 1
A shaded-pole AC fan motor 1 shown in FIG. 13 has conventionally been used as a fan motor for freezing equipment because of the following advantages: the motor can directly operate on an AC power source, has a small number of components, and is inexpensive. This AC fan motor 1 has a high power consumption of 9 to 10 W, a power loss of approximately 90% and generates heat at a temperature of approximately 40xc2x0 C. Moreover, having a thickness of approximately 48 mm, this AC fan motor is relatively large.
Prior Art 2
A DC fan motor 2 shown in FIG. 15 has conventionally been used as a fan motor for freezing equipment instead of AC fan motor 1 because motor 2 has an advantage of requiring a low power consumption. An AC-DC conversion power source 3 is attached to the outside of DC fan motor 2 in order to supply DC power to DC fan motor 2. When motor driving power is obtained by AC-DC conversion power supply 3, voltages are stepped down via a resistor or transformer and thus a power loss is produced. In addition, motor 2 requires a lead connecting DC fan motor 2 and AC-DC conversion power source 3 and this causes the motor to have a more complicated structure and a larger size.
It is an object of the present invention to provide a DC fan motor for freezing equipment or a ventilating fan that has a compact structure as a whole and a small power loss and to provide a method of manufacturing the same.
A DC fan motor in accordance with the present invention has a stator including a stator core, and a rotor placed in the stator core. The stator has the following components: a printed circuit board; the stator core having stator coils; an AC power source connector; a rectifier circuit that rectifies input AC power to obtain high DC voltage; a step-down circuit that obtains DC low voltage from the DC high voltage; a heat shock absorber fixedly attached to the printed circuit board; and a control circuit that controls the stator coils. These components are molded into one body to form a stator using a molding material. The DC high voltage from the rectifier circuit is supplied to the stator coils as a driving power source and the DC low voltage from the step-down circuit is supplied to the control circuit as a control power source. The present invention thus provides a compact DC fan motor for freezing equipment or the like with small power loss and low power consumption and that has a rectifier circuit and a control circuit integrated therein.